Is Performance marketing a bit too much for you? Would you rather provide only the Ad space and inventory and have it managed for you, but not automated like via Google AdSense? Check out Display Advertising and find out if that would work better for you.

If you don't want or can't create relevant content yourself, buy them and then monetize them. Article Underground for example provides members hundreds of new articles that are highly optimized for relevant niche keywords and phrases and not available to everybody to re-print. Only a limited number of members get access to the same content. You can also hire a freelance writer at a Freelance Project Marketplace like eLance.com.

Google AdSense Tool by PromotionWorld. Like DigitalPoint Google AdSense Sandbox Tool, but you can select the Google Ad Format and Color Scheme to get an actual preview of how the Google Adsense Ad would look like.

AdSense Preview - Simulates what ads would appear on a given URL and how they would look like based on the selected Ad Size

Semi-Contextual Advertising - Keyword Targeting

Semi, because no algorithm determines which Ads are shown like with AdSense or YPN.
The Advertiser and/or Publisher have control over the Ads displayed.

ebay AdContext (non-public beta) also supports Keyword targeting as optional feature, if you don't want to rely on eBays ability to determine relevant Ads for your page. The Free Ebay Contextual Advertising Service utilizes the beta service for everybody who was not accepted. It still requires an active Affiliation with eBay through the CJ Affiliate Network

AccessoryAds.com by 7Search.com - Keyword targeted Ads like the Ad further up on this page.

Chitika Display targeted products and you get paid for clicks. You can select the product category you would like to get product ads being pulled from.

AuctionAds.com - Increase the Bid on Your Site's Income! Auction Ads allows you to display live eBay auctions on your website next to your content. You are in control of which type of auctions are shown.